Passes use tags to tell how and when they expect to be rendered to the rendering engine.

Syntax

Tags { "TagName1" = "Value1" "TagName2" = "Value2" }

Specifies TagName1 to have Value1, TagName2 to have Value2. You can have as many tags as you like.

Details

Tags are basically key-value pairs. Inside a Pass tags are used to control which role this pass has in the lighting pipeline (ambient, vertex lit, pixel lit etc.) and some other options. Note that the following tags recognized by Unity must be inside Pass section and not inside SubShader!

LightMode tag

LightMode tag defines Pass’ role in the lighting pipeline. See render pipeline for details. These tags are rarely used manually; most often shaders that need to interact with lighting are written as Surface Shaders and then all those details are taken care of.

Possible values for LightMode tag are:

Always: Always rendered; no lighting is applied.

ForwardBase: Used in Forward rendering, ambient, main directional light, vertex/SH lights and lightmaps are applied.

ForwardAdd: Used in Forward rendering; additive per-pixel lights are applied, one pass per light.

VertexLMRGBM: Used in legacy Vertex Lit rendering when object is lightmapped; on platforms where lightmap is RGBM encoded (PC & console).

VertexLM: Used in legacy Vertex Lit rendering when object is lightmapped; on platforms where lightmap is double-LDR encoded (mobile platforms).

RequireOptions tag

A pass can indicate that it should only be rendered when some external conditions are met. This is done by using RequireOptions tag, whose value is a string of space separated options. Currently the options supported by Unity are:

SoftVegetation: Render this pass only if Soft Vegetation is on in Quality Settings.